import java.util.Arrays;

public class lk1929 {
    public static void main(String[] args) {
        int[] a= {1,2,1};
        System.out.println(Arrays.toString(getConcatenation(a)));
    }
    public static int[] getConcatenation(int[] nums) {
        int n=nums.length;
        int a[]=new int[n*2];
        for(int i=0;i<2*n;i++){
            a[i]=nums[i%n];
        }
        return a;
    }
}
